Electric plug



Aug. 18, 1931. s, M, KENERSQN 1,819,100

ELECTRIC PLUG Filed Sept. 15. 1928 2 Sheets-Sheet l s. M. KENERSON 1,819,100

ELECTRIC PLUG Aug. 18, 1931.

Filed Sept. 15. 1928 2 Sheets-Sheet 2 .x] c 1 I I I I I 1 I I \Y 1 J I 90 55 F ya I fiederlloi :Sfiazzley/Zffamzsaa Patented Aug. 18, 1931 UNITED STATESPATENT OFFICE STANLEY M. KENERSON, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNOR TO STANDARD ELECTRIC TIME COMPANY, OF SPRINGFIELD, MASSACHUSETTS, A CORPORATION 01' CONNECTICUT ELECTRIC PLUG- Application filed September 18, 1&28. Serial No. 805,809.

Objects of the present invention are to prohooked over a flange 15, as shown at 16, the vide an electric plug of the type adapted to fit end of the terminal extending 1nto a oove into a wall receptacle or other jack which is simple and economical in construction, which is durable and reliable in use and which is generally superior to plugs of this typeas heretofore constructed.

The features of the invention will be evident from the following description and claims and the illustration of one .concrete embodiment in the accompanying drawings, in which Fig. 1 is a side view of the plug;

Fig. 2 is a transverse central section on line 22'ofFig.1; Fig. 3 is a longitudinal central section;

Fig. 4 is a bottom plan view with parts removed;

Fig. 5 is a sectional view similar to Fig. 2, illustrating an optional construction" A Fig. 6 is an end elevation of a modification;

Fig. 7 is a section on line 77 of Fig. 6 5

Fig. 8 is a central longitudinal section taken at right angles to the section of Fig. 7 showing the plug inserted in a jack;

I Fig. 9 is a front elevation of a modification;

Fig. 10 is a central longitudinal section of a further modification adapted for two cables; and

Fig. 11 is a front elevation of the modification shown in Fig. 10. The particular embodiment of the invention shown in Figs. 1 to 4 com rises top and bottom parts 1 and 2 of suita le insulating material, screws 3 for holding these parts together, five contact terminals 4, 5, 6, 7 and 8 fastened to the bottom part 2 by means of tubular rivets 9 an elongate metallic bar 10 secured to the bottom part by means of a screw 11, and two spring detents 12 and 13 fastened to the bottom ets 14.

As shown in Figs. 2 and 3, the upper surface of the bottom art 2 is recessed to accommodate the con uctors which are connected to the contact terminals 4 to 8 inclusive within the tubular rivets 9. As shown in Fig. 2 the contact terminals 4 to 8 inclusive part by means of rivare L-shaped and one end of-each terminal is extending longitudinally of the lower ace of the part 2, two such grooves 17 and 18 being provided for the two series of terminals 4, 5, 6 and 7 8. By hooking the terminals as aforesaid, each terminal may be held firmly in position by means of a singlerive't 9.

The fasteners 12 and 13 are formed of spring material and fit in notches 24 in the ends of bar 10 and each is provided with a shoulder 19 for engagement behind the plate 20 of the wall receptacle. The part 2 1s recessed along its lower edges to accommodate the face plate 21 of the wall receptacle, it being understood that the parts 20 and 21 form no part of the lug but' merely cooperate therewith to hol the plug in operative position with the terminals 4 to 8 inclusive engaging the terminals of the jack mounted in the wall receptacle.

In order to prevent the plug from being inserted in the jack in reversed position, a lug 22 is mounted on the plug to extend into a recess 23 of the wall receptacle when the plug is inserted in the proper position, the lug 22 obstructing the insertion of the plug in the reverse position. The plate 21 may be secured over the plate 20 in any suitable way as by spring clips, one of which is shown at 25 in Fig. 2. In the optional arrangement 4 shown in Fig. 5, a forward projection of the plate 20 is received within a supplemental recess on one side of the bar 10, to insure proper insertion of the lug 10.

Figs. 2 and 3 illustrate one form of means for clamping the covering of the cable 40 between, the body 2and cover 1 of the plug to relieve strain on the cable wires resulting from pulls on the cable 40. This means comprises a plate 50 fixedly or detachably mounted in a recess in the cover 1 and having an opening somewhat smaller than the opening in the cover 1 so as to indent the periphery of the cable covering when the cable is pulled through the cover. Thus when the cover 1 is forced against the back of the body 2 by means of screws 3 the projecting portion of the cable covering is s ueezed etween the plate 50 and the back of ody 2, causing it to bulge outand be clamped in position as illustrated in Figs. 2 and 3.

front plate of the receptacle containing the jack 34 (Fig. 8) into which the plug is to be inserted, thereby to prevent the plug being inserted into the jack in reverse position.

Instead of the spring fasteners 12 and 13,

v the modification shown in Figs. 6 to 9 inclusive is rovided with circular lugs 33 having rounde ends adapted to engage spring contact fingers 35 of the jack frictionally to hold the plug in position with the contact pieces 4 to 8 engaging the contact pieces 36 of the jack respectively, this jack being described and claimed in a copending application filed on even date herewith. The lugs 33 are mounted in recesses 37 in the forward face of the body 2' of the plug at each end of the central projection 30 by means of screws 3 extending through the cover 1 and thence threading into the lugs. Thus the screws 3 serve the double function of holding the cover 1' on the body 2' and also holding the lugs 33 in lace.

he means for gripping the covering of the cable 40, to relieve the strain on the wires when the cable is pulled, is somewhat different from that shown in the preceding figures. A conical member 41 is mounted on the rear face of the body 2' in alignment with the cable opening of the cover to force the cable.

covering 42 outwardly against the peripheral edge 43 of the cable opening and thereby clamp the cable covering between this conical piece and the cover when the cover is forced against the body 2 by means of screws 3'. T e conical part 41 may be formed integrally with the body'2 or it may be in the form of a separate piece of insulation bearing on the back of ,the body 2' or preferably seating in a recess 44 as shown in the figures. In assembling the parts the cable is first inserted through the cover 1', the wires are then spread outwardly from the axis of the cable so as to be distributed around the conical projection 41, the ends of the wires are then connected to the contact pieces 4' to 8 inclusive by means of the connectors 45, and'the cover 1' is then forced into place against the back of the body 2, whereupon the cable coveri'ng is clamped as aforesaid to relieve the strain on the wires 46 resulting from pulls on the cable 40 to which plug cables are ordinarily subjected.

The modification shown in Figs. 10 and 11 differs from that shown in Figs. 6 to 9 inclusive only in thatthe plug is constructed for attachment to two cables leading from the same contact pieces, as for example in the case of two bed switches in a hospital ward being connected to the same plug. In this modification the lugs 33 are held in place by screws 47 other than the screw 48 which holds the cover 1" on the body 2'. The cover 1" is provided with two cable openings and two conical pieces 41" in alignment with the openings respectively for spreading the cable coverings as above described.

I claim 1. An electric plug comprising a body of insulation having a central projection on its forward face, a plurality of contact pieces mounted on the body on opposite sides of the projection, the forward ends of the ends of the contact pieces being hooked over the projection, a bar secured to the face of the projection over said hooked ends, said bar having notches in its opposite ends, and holding lugs Y received in said notches and fastened to the body at opposite ends of the projection for frictionally retaining the plug in a jack, the lugs being insulated from the contact pieces and projecting forwardly beyond the projection and the contact pieces.

2. An electric plug comprising a body of insulation having a central projection on its forward face, a cover on the rear side of the body, a plurality of contact pieces mounted on the body on opposite sides of the rojection; the forward ends of the ends of t e contact pieces being hooked over the projection, holding lugs fastened to the body at oppos te ends of the projection for frictionally retaining the plug in a jack, the lugs being insulated from the contact pieces and projecting forwardl beyond the projection and the contact pieces, and fasteners extending through the cover and body into the base of the lugs for securing both the cover and the lugs to the body.

Signed by me at Boston, Massachusetts thls fifth day of September, 1928.

. I STANLEY M. KENERSON. 

